1. Field of the Invention
The present invention relates to electrical connector assemblies, and more particularly to a connector assembly having two mating connectors used for high-speed signal transmission.
2. Description of Related Art
High-speed digital electronic apparatus, such as certain communication equipments and computer servers, require fast and accurate signal transmission. These apparatus have electronic components including connectors, wires, circuit boards, and integrated circuit packages. In low-speed applications, these components can function normally in cooperation with each other. However, in high-speed applications, conductivity and other electrical characteristics of these components become critical in ensuring that the electrical performance of the apparatus as a whole is satisfactory.
The faster the signal transmission required of an electronic apparatus, the harder it is to build suitable electrical connectors for the apparatus. One of the primary electrical factors affecting high-speed performance in connectors is cross talk mutually induced between two adjacent contacts of the connector. The intensity of cross talk depends on the distance between the two adjacent contacts.
Today, as electrical products become smaller and smaller, so too do their components such as connectors. In addition, the number of contacts in contemporary connectors is increasing due to the demand for more signal transmission paths and faster transmission speeds. Therefore, the distance between adjacent contacts inside a typical connector is becoming less and less. Cross talk induced between the contacts is becoming increasingly significant, and needs to be carefully addressed.
One way to deal with cross-talk inside a connector is to establish a ground reference means between every two contacts of the connector. U.S. Pat. No. 5,645,436 shows an example of a conventional connector system including jack and plug connectors. Each connector includes a plurality of signal contacts arranged in several rows and columns in an electrically insulative body. Signal paths comprising mutually engaged contacts of the jack and plug connectors have ground means alternately located therebetween. As a result, the number of contacts installed inside the jack and plug connectors is increased. In addition, manufacturing of the ground means and signal contacts becomes significantly complicated due to the different structural designs of the signal contacts and ground means. Furthermore, the increased number of contacts results in more difficulty when installing the contacts into the connector housing, because only a smaller pitch between every two adjacent receiving holes in the housing is available. These difficulties in manufacturing increase costs significantly, and do not necessarily guarantee better electrical performance.
Another way to deal with cross talk is to transmit differential signals in a connector, as described in the book High-Speed Digital Design (by Howard W. Johnson and Martin Graham, pp. 319–320). Such connector can provide better electrical performance with regard to impedance matching, cross talk reduction, and electromagnetic interference (EMI) reduction. What is needed is an electrical connector transmitting differential signals, which can overcome the above-described shortcomings of conventional connectors.